Field of the Invention
The present invention relates to a process for fastening components on a hollow shaft, in particular to manufacture a constructed cam shaft, according to a process for fastening cam components on a hollow shaft in which the cam components are put into specified positions on the hollow shaft and the hollow shaft is expanded by introducing a pressure medium in order to fasten the cam components onto the shaft.
The EP C257175 B1 discloses a process for the manufacture of a constructed cam shaft, where the components are fastened on the outer periphery of a pipe by introducing an expanding mandrel into the pipe. The shell of said expanding mandrel has at least two pairs of sealing rings, whereby the distance between the two sealing rings of each pair of sealing rings is equivalent to the axial stretch of the respective fastening place for a component. The pairs of sealing rings are spaced apart on the expanding mandrel in accordance with the spacing of the components on the pipe. Each pair of sealing rings forms an expanding space between its two sealing rings, said expanding space being connected to a central pressure channel of the expanding mandrel by means of a connecting channel. When the pressure medium is introduced into the central pressure channel, the result is a targeted expansion of the pipe between the sealing rings of a pair of sealing rings in order to fasten the components. The problem with this process is that first of all the expanding mandrel is complicated in its construction and secondly also comparatively difficult to handle, because it has to be accurately oriented relative to the fastening sites.
The EP 0257175 B1 also describes a process, wherein the use of an expanding mandrel can be avoided, according to FIG. 1, by laying the pipe into the central cavity of a matrix, which comprises two halves of a matrix that can be clamped together. Prior to laying the pipe into the matrix, the components are arranged on it. To receive these components, the matrix has suitable recesses. The components are heated and/or the pipe is cooled so that a temperature differential is produced.
Through the temperature differential a further shrink fitting of the components on the pipe takes place, when fastening the components through expansion of the entire pipe. It is easy to see that such a process is relatively time consuming and, therefore, cost intensive, because, on the one hand, the matrix is complicated on account of the need to provide recesses to receive the components; and, on the other hand, producing different temperatures at the pipe or the components is also complicated and expensive. The fastening procedure requires such an interaction between the expansion operation of the pipe and the shrink fitting of the heated components on the deformed pipe areas that in the area of the components the components rest against the inner surfaces of the same.